Access to common areas

I am staying on a builder floor of 6 floors side by side and i am staying 2nd floor on one side. Out of 6 floors, apart from 2 floors (ground floor on my side and my floor), all other 4 floors with roof are related to single owner. That single owner is well known former politician and when we bought our floor, we forgot to check that the roof access from other side of the building which is in complete control of that single owner. Now, that owner says: - Parking on our side is being owned by him - Roof is in his control so he is now forcing us to get off the water tanks from roof Also, he mentally harrasing us from letting us go to the roof to see the problems occurs with water supply. Water tanks kept on roof is having some leakage due to which the sippage came down and his floors getting damaged. We told him that we are ready to fix the sippage root cause but he just keep on saying get off the water tank from roof. Please help me understand is this at all legally possible for him own the roof (stopping us to go to roof) and the parking space down the building. Also, confirm how to have the issues sorted out.